There is a system that causes a plurality of virtual computers to operate on a single server device and assigns the virtual computers to multiple terminal devices, respectively, while the terminal devices are connected to the server device through a network. The virtual computers are called virtual machines (VMs). In the system, operating systems (OSs) run on the virtual machines that operate on the server device. Users operate the terminal devices so that the terminal devices each use the OS of the virtual machine assigned to the terminal device. In other words, the server device is used as a desktop computer for the terminal devices.
JP4242819 discusses a technique for transferring virtual machines between the server device and the terminal devices through a network. In JP4242819, information (data) that is used to cause each of the virtual machines to operate on the server device is synchronized between the server device and the terminal device so that an operating environment that is the same as the server device is achieved in the terminal device. Thus, even when the terminal device is in an offline state or is not connected to the server device, a user operates the terminal device so that the terminal device uses the virtual machine.